A liquid crystal optical device is known that utilizes the birefringence of liquid crystal molecules to change the distribution of the refractive index according to the application of a voltage. There is a stereoscopic image display device that combines such a liquid crystal optical device with an image display unit.
Such a stereoscopic image display device switches between a state in which an image displayed on the image display unit is caused to be incident on the eyes of a viewer as displayed on the image display unit and a state in which the image displayed on the image display unit is caused to be incident on the eyes of the viewer as multiple parallax images by changing the distribution of the refractive index of the liquid crystal optical device. Thereby, a high definition two-dimensional pixel display operation and a three-dimensional image display operation are realized, where the three-dimensional image display operation includes autostereoscopic viewing with the naked eyes due to the multiple parallax images. A comfortably-viewable display is desirable for such a display device.